An automotive steering shaft is arranged so as to penetrate a panel through an opening provided on the panel which separates a vehicle compartment and an engine room. Between an edge of an opening of the panel and the steering shaft, there is provided a dust cover for the steering shaft in order to prevent rainwater, dust, the outside air, noise and the like from entering the vehicle compartment. It is unavoidable for the steering shaft to move with respect to the opening provided on the panel, such as, for example, to incline or deviate, for adjusting the height of a steering wheel, or due to vibrations or the like during automobile traveling. Accordingly, the dust cover for the steering shaft is provided with bellows. The bellows are formed of easily-deformable soft rubber material, and the deformation of the bellows allows the dust cover to follow the oblique movement of the steering shaft.
As a conventional dust cover for a steering shaft, there is one disclosed in Japanese Patent Publication No. 2001-324018. Referring to FIG. 17, the dust cover 100 for a steering shaft that has a shaft sealing portion 101 that passes the steering shaft therethrough and is in contact with the steering shaft, and two bellows portions 102 and 102 having an inner peripheral end coupled to the shaft sealing portion 101 and an outer peripheral end attached to a panel fixing member 103. The shaft sealing portion 101 and the two bellows portions 102 and 102 are formed of rubber material and are integrally formed by using metal mold. In this technique, sound insulating properties are enhanced by providing these two bellows portions 102 and 102. Also the two bellows portions 102 and 102 and the shaft sealing portion 101 passing the steering shaft therethrough, are integrally formed, so that an operation of incorporating to a vehicle body is facilitated.
Japanese Patent Publication No. 2001-324018 is citied as a material reference here.